Page 241 - 360.revista de Alta Velocidad - Nº 5

Soil stabilization in new railway construction

and standard organizations are continuously studying alternatives to the traditional so‐
lution that they confer greater reliability and stability to the high performance railway
movement.
It is in this context where an alternative to the classic structure is proposed, based on
the use of layers treated with hydraulic binders. The use of both binders, lime or cement,
applied and mixed with the soil leave a structure more resistant. They reduce the tensions
on the platform and increase the transverse strength, both in the vertical loaded via (which
allows better performance in the railway operation), as in the discharged via (improving
stability of the track against the efforts of thermal origin). The desired stiffness of the
soil can be obtained, and even, this rigidity can change in the path depending on the soil
characteristics and the dosage of binder. (modulus variable in the material).
Other advantages that these solutions based on the use of layers treated with hydraulic
binders can provide are:

• Use of materials of the working path what allows economies in the building phase.
It avoids the quarries (inside and outside the working unit) and the need for the
supply by other agents (that lets all internal tasks coordination and an important
improvement in the speed of execution).

• It is a more environmentally friendly solution: avoiding opening or quarrying and
vehicles of heavy transport by roads, with the damage that they do. In addition
also this technique prevents the need for landfill sites where to send the soils that
otherwise should be removed from the work.

• Use of manufacturing equipments that exist normally in the works. It is not necessary
to incorporate special machinery.

• Improves the impermeability of the base layer, obtaining greater stability in time
(durability) and better performance against water. This increase of tightness is in
addition to the 2% pumping that must be given to drain the water that has seeped
through the ballast.

3. Traditional starting situation

Designers used to have abacuses to determine the thickness of the layers in the traditional
railway (up to 200 km/h speed), according to the following parameters:

• Characteristics of the soils that constitute the platform on the stretch of railway
considered.

• Characteristics of the platform as a whole.
• Climatic conditions of the location of the platform area.
• Characteristics of the traffic in the considered section.

• Characteristics of the superstructure.

Designers have been made various adaptations and extrapolations in the high speed train
case in Spain. The structure that is used is reflected in the figure below:

International Congress on High-speed Rail: Technologies and Long Term Impacts - Ciudad Real (Spain) - 25th anniversary Madrid-Sevilla corridor 239